I have removed the old users
Please do a factory reset, and then set it up again ‘as new’. Then it wouldn’t have any trace from previous users.
Reset or restore your Apple TV to its factory settings - Apple Support
I keep getting a sign saying not connected to the internet
You would need to enter the credentials for your own home network for Wi-Fi, or use ethernet.
Settings﹥Network﹥
when I try to sign in with my Apple iCloud ID it still won’t connect
I presume that has to do with the previous, as the entered Apple ID would be validated through Apple’s servers (thus needing internet connectivity).